Chelating resin and process for preparing the same

ABSTRACT

A novel, easily regeneratable, high-performance chelating resin and process for preparing the same. More in particular, a crosslinked polymer consisting mainly of an aromatic vinyl monomer having a polyalkylene polyamine functional group containing an iminodipropionic acid group or an iminodi- Alpha methylpropionic acid group, and process for preparing the same. Because chelating resins of the present invention have pendant functional groups attached pendantly thereto, at least one iminodipropionic acid group or iminodi- Alpha -methylpropionic acid group and at least two nitrogen atoms, it has a very large capacity for adsorbing heavy metals per unit volume of chelating resin. Moreover, because the stability of the chelate of said iminodipropionic acid group or iminodi- Alpha -methylpropionic acid group with heavy metal ions is relatively low, regeneration from an adsorbent with heavy metals is easy. According to the process a high-performance chelating resin can be prepared, having a very high ability to absorb heavy metals. It is easily regeneratable, which has heretofore been inexpensively unattainable by conventional processes and is produced by a new process which is high in industrial practical value.

United States Patent twi Aya et al.

[ Aug. 12, 1975 i 1 CHELATING RESIN AND PROCESS FOR PREPARING THE SAME [75] Inventors: Toshlhlko Ayn: Kuumlsa Chiba; Zenzl lzumi, all of Nagoya. Japan [73! Assignee; Tony industries. Inc.. Tokyo, Japan {22] Filed: Nov. 18. 1974 [2i I Appl. No.: 524.353

(30] Foreign Application Priority Data Nov. 2i. i973 48430083 Mar. 5. i974 Japan................................ 49-24736 [52] US. Cl...... 260/8038; 260/882 5; 260/915 A 15 l] int. Cl. C08F 210/00; COBF 2l2/UO I58] Field of Search 260/831 S. 93.5 A. 80.78

[36] Relerences Cited UNITED STATES PATENTS 3,645,997 2lll72 D'Alclio Zfll/MLI FOREIGN PATENTS OR APPLICATIONS 7071147 4/]954 United Kingdom 260/882 5 OTHER PUBLICATIONS G. Kuehn et al.. Makromol Chem. (i967). S. Chaherckto et ul.. J. Amer. Chem. Soc. 75. i953). 2888-2892.

Primary Examiner-Joseph L. Schol'er Asslstanl Examinen-Herbcrt .I. Lilling 57 ABSTRACT resin. Moreover because he stability of the chelate ol said iminodipropionic acid group or iminodi-ot-methylprupionic acid group with huitv metal ions is relatively low, regeneration from an adsorbent with heavy metals is easy.

According to the process a higl1-perfort1tance chclatirlg resin can be prepared. having a very hi h ability to ahsorb heavy metals it is rcgencratable. which has heretofore been inexpensively unattainable by conventional processes and is produced by a new process which is high in industrial practical value.

7 Claims, No Drawings CHELATING RESIN AND PROCESS FOR PREPARING THE SAME BACKGROUND OF THE INVENTION high abilit to absorb heavy lllulillS. The fact that the stability of the chelate is lower means that the conditions for elution of heavy metals from an adsorbent with heavy metals become easier In fact. it has been confirmed that regeneration of the type of iminodipropionic acid is easier than that of the type of iminodiacetic acid. This characteristic of easy regeneration is very important for a chelating resin in the sense that it has a long recycle lifetime when it is utilized as an ad sorbent for water treatment.

For synthesizing a chelating resin of this type of iminodipropionic acid. the following may be cited by way of example:

lating resins have become active. In the field of chelat ing resins. the work that has been studied most broadly for a long time is the so-called type of iminodiacetic acid in which an N-methylene iminodiacetic acid group is introduced into the aromatic nuclei of erosslinked styrene-divinyl benzene copolymer beads. A chelating resin of this typs has many characteristics such as l high adsorbing capability for heavy metals. (2) excellent chelatc-forming capability and selective adsorbing capacity for heavy metals, (3) high stability of chelate. and (4) regenerability.

With reference to the so-called type of iminodipropionic acid in which an N-methylene iminodipropionic acid group is introduced into the aromatic nuclei of erosslinked styrenedivinyl benzene copolymer beads. similar to this type of iminodiacetic acid. a few reports have been written (for example, G. Kuehn and E. Hoyer, Makromol. Chem., 108. 84 94 I967) and Y. B. Trostyanakaya and 0. Z. Nefcdova, Vysokomol. Soyed. 5 (l), 49 56 H963).

We have conducted a detailed examination with reference to the type of iminodipropionic acid. and have confirmed that characteristics which are about the same as those pointed out with respect to this type of iminodiacetic acid are present in this type also. it becomes clcar that of said characteristics. with respect to the stability of chelate. the type of iminodipropionic acid shows a value considerably lower than that of the type of iminodiacetic acid. Indeed. the type ofiminodi propionic acid is such that it shows a relatively low stahility of chclatc with heavy metal ions in spite of its Of the above two processes (A) and (B). process (B) is complicated in its reaction step. Moreover. at the stage of introducing sodium-B-chloropropionate to amino methylated polystyrene (also because this is a polymer reaction), it is quite difficult simultaneously to introduce two propionic acid groups thereto. though it is relatively easy to introduce one propionic acid group per amino group. The process (B) has the drawback that it is not possible to form an iminodipropionic acid group effectively. Therefore. this process has almost no practical value.

On the other hand. the process (A) is theoretically practicable. However. because the polymer-matrix having a chloromethyl group is hydrophobic, it does not simply react with a water-soluble nucleophile such as iminodipropionic acid or sodium iminodipropionate. and it is actually difficult to practice this process.

One means for improving process (A) is (C) to make the polymer-matrix hydrophilic in advance. A few proposals have been made. including Japanese Patent Application Publication Nos. 69] 1962, 3699/1965. 28414/l97l and 28514/197].

This process (C) is considerably effective. However. on the other hand, the number of reaction steps increases and an excess of reaction by-products must be removed. Thus. the production step becomes complicated, and process (C) is not necessarily satisfactory in respect of reaction yield and ability to absorb heavy metals of the chelating resin produced.

For improving the process (A). another procesd (D) has been suggested. This consists of using a hydrophobic compound (specifically iminodipropionitrile or alkyl iminodipropionate. etc.) as a source of iminodipropionic acid. reacting the same with a chloromethyl atctl polystyrene matrix in the presence of a swelling solvent and thereafter carrying out saponification to produce an iminodipropionic acid group on the aromatic rings. This is referred to, for example. in Y. B. Trostyanskaya and G. Z. Nefedova. Vysokomol. Soyed., 5 (ll, 49 56 (1963).

Various reaction conditions with reference to the aforesaid process (D) were examined. It was found that this process is, to be sure, effective in introducing an iminodipropionic acid group to the polystyrene side chain. However, the reaction yield at the reaction stage of chloromethyl groups with irnino groups reaches only a relatively high level, so that this process (D) is very unsatisfactory for synthesizing high-performance chelating resins.

We have now discovered that a novel chelating resin having excellent adsorbing ability for heavy metals, and having excellent regenerating ability, is obtained in a very effective reaction by using, as the compound to which the iminodipropionic acid group or iminodi-amethylpropionie acid group is to be introduced, a polylalkylene polyamine derivative (hereinafter referred to as an intermediate ofa functional group) having, in the molecule. at least one group selected from the class consisting of iminodipropionitrile. iminodi-amethylpropionitrile, alkyl iminodipropionate and alkyl iminodi-a-methylpropionate, wherein the alkyl groups have l 8 carbon atoms, and at the same time containing at least one primary and/0r secondary amino group.

Further. it has been discovered that conditions for synthesizing the aforesaid intermediate of a functional group have certain characteristics, which will be disclosed in detail hereinafter. We have succeeded in unifying a step for synthesizing the intermediate of a func tional group (hereinafter referred to as step S) together with an additional reaction step of the intermediate of a functional group to a crosslinked halomethylated polymer (hereinafter referred to as step H), with unexpected great benefit.

The following are characteristics ofstep S" for synthesizing the intermediate ofa functional group:

l. The reaction temperature, reaction pressure and stirring conditions are roughly similar to those of step H.

2. The reaction atmosphere and catalytic activity are basically similar to those of step H.

3. Partly because the reaction proceeds stoichiometrically, the amount of by-product is small, and this by-produet does not obstruct step H.

SUMMARY OF THE INVENTION The present invention provides a novel highperformance chelating resin having a crosslinked poly mer structure whose main structural unit is the struc ture (II or (II):

t In llt (um wherein l represents an integer from l 8, m represents an integer from U 8, n represents an integer of 2 12, M represents hydrogen. a univalent alkali metal ion such as sodium, potassium or lithium. or NH,+, R represents hydrogen or methyl, X, Y and Z each represents hydrogen or a group selected from the class consisting of alkyl having l 8 carbon atoms, hydroxyalkyl having l 8 carbon atoms, aromatic having 6 9 car bon atoms, aralkyl group having 7 10 carbon atoms and A-COOM, wherein A stands for divalent alkyl residual group having I 8 carbon atoms and M has the aforementioned meaning. Further, the present invention provides a process for preparing an easily regeneratable, high-preformance, novel chelating resin having a crosslinked polymer structure whose main structural unit is the aforesaid structure (I) and/or (II), which process comprises reacting a halomethyl group bonded to aromatic nuclei of a crosslinked polymer consisting mainly of an aromatic vinyl monomer with a polyalkylene polyamine derivative having'in the molecule at least one kind of group selected from the class consisting of iminodipropionitrile, iminodi-a-methylpropionitrile. alkyl iminodipropionate and alkyl iminodi-a-methyl propionate wherein the alkyl groups have l 8 carbon atoms, at the same time, having at least one primary and/or secondary amino group in the presence of a swelling solvent, and thereafter carrying out hydrolysis of the reaction product in the presence of an acid or alkali to produce at least one of group selected from the class consisting of iminodipropionie acid, iminodi-amethylpropionic acid, inimodipropionate and iminodi-oz-methylpropionate. Hereinafter, this process will be referred to as the first synthesizing process. Further, the present invention provides a process for preparing an easily regeneratable, high-performance, novel chelating resin having a crosslinked polymer structure whose main structural unit is the aforesaid structure (1) and/or (II), which process comprises reacting simultaneously a halomethyl group bonded to aromatic nuclei of a crosslinked polymer consisting mainly of an aromatic vinyl monomer with (A) a polyalkylene polyamine derivative having in the molecule at least one primary amino group and one secondary amino group and (B) at least one kind of unsaturated compound selected from the class consisting of acrylonitrile, methyacrylonitrilc, alkyl acrylate and alkyl methacrylatc wherein the alkyl groups have 1 8 car hon atoms in the presence of a swelling solvent, and thereafter carrying out hydrolysis of the reaction product in the presncc of an acid or alkali to produce at least one group selected from the class consisting of iminotlipropionic acid. iminotlioz-mcthylpropionic acitl. iniinodiprupionatc and iminotli-uinc-thy lpropionate Hereinafter. this process \till he rc fcrrcd to as the second synthesizing process."

cess (D), it is possible to introduce at a high reaction yield and more effectively an iminodipropionic acid group or an iminodi-a-methylpropionic acid group to aromatic nuclei on polystyrene side chains, which is believed to be due mainly to the following reasons: the imino groups of the iminodipropionitrile, iminodi-amethylpropionitrile, alkyl iminodipropionate and alkyl iminodi-a-methylpropionate acquire reduced basicity under the influence of electronwithdrawing groups and the reactivity of the secondary hydrogen is reduced as compared with the conventional secondary amines, said primary or secondary amino group has a relatively high basicity, because the primary or secondary amino group in the polyalkylene polyamine derivative containing at least one group selected from the class consisting of iminodipropionitrile, iminodi-amethylpropionitrile, alkyl iminodipropionate and alkyl iminodi-a-methylpropionatc and at least one primary and/or secondary amino group of the present invention is chemical-structurally separated from the iminodipropionitrile group. iminodi-a-methylpropionitrilc group, alkyl iminodipropionate group and alkyl iminodi-amethylpropionate group by an alkylene group in the molecule. it is considered that such primary or secondary amino group maintains a high reactivity as nucleophile reagent because of that.

The second synthesizing process of the present invention has the advantage that by adding, en masse or in portions, a mixture of polyalkylene polyamine derivative (component A) and an a,B-unsaturated monomer such as acrylonitrile (component B) in a composition corresponding to the objective functional group [for example. in the case of said reaction example (2), adjusting the molar ratio of diethylene triamine to acrylonitrile to 1/4] in a swelling solvent containing a crosslinked halomethylatcd polystyrene, it is possible to carry out a synthetic reaction of an intermediate of a functional group (step S) and an introductory reaction of the polystyrene side chain to aromatic nuclei (step H) in the same reactor. Moreover, after completion of the reaction, it is possible to separate the resulting resin by filtration and to recover the unrcacted component and solvent from the filtrate by, for example, distillation, for reuse. Accordingly, the second synthesizing process of the present invention has the capability of simplifying the reaction process including the reaction step and the aftentrcatmcnt step, shortening the entire reaction period and preparing a high-performance chelating resin having an iminodipropionic acid group or an iminodi-a-methylpropionic acid group economi cally, in which sense the second synthesizing process drastically rationalizes the first synthesizing process,

A crosslinked polymer consisting mainly of an aromatic vinyl monomer which may be used in the present invention (hereinafter referred to as a base resin") may be prepared by polymerizing a mixture of an aromatic vinyl monomer such as styrene, vinyl toluene, a-methyl styrene, ethylvinyl benzene, isopropylvinyl benzene, ethylvinyl toluene, archlorovinylbenzene and ar-chlorovinyl toluene with a crosslinking agent such as divinyl benzene, divinyl toluene, divinyl pyridine, divinyl naphthalene, trivinyl benzene, trivinyl naphthalene, diallyl dicarboxylate such as diallyl adipate and diallyl phthalate, methylene bis acrylamide and ethylene glycol dimethacrylate in the presence of an ordinary initiator of radical polymerization such as benzoyl peroxide, lauroyl peroxide, t-butyl peracetate, t-butyl perbenzoate, azobisisobutyronitrile and azobiscyclohcxanenitrile. At this time, it is possible to replace a part of said aromatic vinyl monomer by other non-aromatic vinyl monomers, It is appropriate that the amount of the crosslinking agent added upon preparing this base resin is 0.2 20 (preferably 0.5 l5) by weight based on the weight of the base resin produced.

The shape of the base resin of the present invention is not particularly limited and may include beads, film, blocks, flakes or powders. However, when utilized as a chelate adsorbent for general use, beads are especially preferred. Base resin beads may be prepared easily by suspension polymerization (in water) of a mixture of an aromatic vinyl monomer, a cross-linking agent and a radical polymerization initiator in the presence of an inorganic compound which is hardly soluble in water or in a water-soluble polymer. when utilized in a manner requiring mechanical strength, porous base resin beads are useful base resins.

lntroduction of a halomethyl group into the base resin is easily accomplished by, for example, reacting a mixture of paraformaldchyde with hydrogen chloride, chloromethylether or bromoethylether with the base resin in the presence of a catalyst of the Friedel-Crafts type such as zinc chloride, stannic chloride or aluminum chloride. The reaction is ordinarily carried out at 20 C, by which reaction 2 l5 (ordinarily 5 10) units of halomethyl groups are introduced to 10 units of aromatic nuclei in the base resin.

Polyalkylene poly-amine derivatives (intermediate of a functional group) having in the molecule at least one group selected from the class consisting of iminodipro pionitrilc, iminodimmcthylpropionitrilc. alkyl iminodipropionate and alk \l uninodi-rrmethylpropionate wherein the alkyl groups have 1 r 5.

carbon atoms, and at the same time having at least one primary and/or secondary amino group which may he used in the first synthesizing process of the present in: vention is a compound represented by the following general formulas (Ill) or (IV).

(III) Y H I wherein 111 represents an integer from 8. II represents an integer from 2 l2. 1 represents an integer from 1 8, R represents hydrogen or a methyl group. R represents an alkyl group having 1 8 carbon atoms.

and-X and Y each represent hydrogen, an alkyl group HOCH CH -NH-CH -CH -N(CH CH CN )2 14,

These intermediates of functional groups may ordi narily be synthesized by properly combining HN(CH- ,CH- ,CN) NH;,, CH NH CI(CH ),,CI. HOCH CH Cl, H NCH CH CN. In other processes, examples (3), (6), (8). (9). (10). (1 l and (12) may be synthesized easily and very inexpensively simply by using the Michael addition reaction of acrylonitrile with commercially available polyalkylene polyamines. Therefore, the processes of the present invention are very practical and valuable.

As examples of intermediates having functional group (IV), the products obtained by substituting for the respective CN group a COOCH;, group or a -COOC H group may be cited, and these esters may be synthesized easily by blowing a dry hydrogen chloride gas into a methanol or ethanol solution of said nitrile compounds.

In the case of the second synthesizing process which carries out simultaneously a synthetic reaction of an intermediate ofa functional group (step S) and an introductory reaction of polystyrene side chain to aromatic nuclei (step H) in the same reactor without synthesizing the intermediate of the functional group in advance. it is possible to use a polyalkylene polyamine derivative represented by the following general formula (V) and acrylonitrile. methacrylonitrile. alkyl acrylate whose alkyl group has l 8 carbon atoms or alkyl methacrylate whose alkyl group has 1 8 carbon atoms (hereinafter referred to as the unsaturated compound fdr the Michael reaction).

wherein land In each represent an integer from O 8, n is an integer from 2 12, X and Y each represents hy' drogen. alkyl group having I 8 carbon atoms. carboalkoxy alkyl group having 3 18 carbon atoms. a hydroxyalkyl group having I 8 carbon atoms. an aromatic group having 6 9 carbon atoms and an aralkyl group having 7 10 carbon atoms.

The reaction of an intermediate of a functional group in the first synthesizing process, a polyalkylene polyamine derivative (component A) in the second synthesizing process or an unsaturated compound for the Michael reaction such as acrylonitrile (component B) with a crosslinked halomethylated polymer base resin may be practiced in the presence ofa swelling solvent such as benzene, toluene. ethyl benzene. chlorobenzene. carbon tetrachloride, l.l.l-trichloroethane. tetrachloroethane, ethylene dichloride, dioxane. tetrahy drofuran and dimethyl forrnamide at a reaction temperature of about 20 200 C for a reaction period of about 0.5 I00 hours. At this time. a reaction catalyst is not necessarily required. However. when a strong base catalyst such as caustic alkali or an alkali metal alkoxide is used. the reaction rate is accelerated. which is advantageousv Hydrolysis of a nitrile or ester group of an intermediate of a functional group introduced to the side chain of the base resin may be practiced easily by utilizing an aqueous reaction using a strong acid such as hydrochloric acid or sulfuric acid or a strong base such as caustic alkali at a reaction temperature of about 30 200 C (preferably about 50 120 C). For example. when such a nitrile or ester group is treated in concentrated hydrochloric acid under reflux conditions for about 4 8 hours. it is possible to obtain about l7( hydrolysis.

Hereinbelow, the present invention will be explained in further detail by reference to examples. These will refer to a selective adsorption test for cupric ion, which is used for testing the performance of the chelating resin of the present invention.

in this test, a 300 ml beaker. I30 ml of Clark Lubs buffer solution having a pH of 6. 20 ml of 0.] M cupric sulfate aqueous solution and 4.5 g of sodium chloride were placed. Thereafter, 0.50 g of a chelating resin was added thereto. and the resulting mixture was stirred by a magnetic stirrer. After carrying out two adsorption reactions for two different predetermined times 1 hour and 2 hours), two different samples of superna tant liquid were taken by means ofa ml pipette from this mother liquid.

Next, 85 ml of distilled water were added to l5 ml of each sample, the resulting mixture was neutralized with l N sodium hydroxide, and subsequently 2 ml ofa buffer solution of ammonium chloride and ammonium hydroxide having a pH of l0 were added to the resulting mixture. Four or five drops of a pyrocateeol indicator were added to the resulting mixture, and it was titrated with a 0.05 molar EDTA standard solution to determine the amount of residual cupric ion in the mother liquid.

EXAMPLE A Preparation of the base resin (No. l

Letting u be any number less than 1000, a mixture containing 1,000 0) grams of styrene. 0 grams of divinyl benzene in technical grades (consisting of approximately 55% by weight of divinyl benzene and approximately 45% by weight of ethylvinyl benzene), 5 grams of benzoyl peroxide, 2 liters of deionized water, grams of poly(sodium methacrylate), 20 grams of s0 dium dihydrogen phosphate and l00 grams of sodium chloride was charged into a 5-liter autoclave equipped with a theromometer. a nitrogen gas inlet tube and a mechanical stirrer. After replacing air in the upper space with nitrogen, the autoclave was sealed and sus pension polymerization was carried out with stirring under the nitrogoen atmosphere at 100 C for 8 hours.

The polymerization mixture was then cooled and the base resin beads were separated by filtration. The degree of crosslinking of the resulting base resin was 0.055 (1%.

EXAMPLE 8- Preparation of base resin (No. 2): Macro reticular type A mixture of SIS g of styrene, 182 g of divinyl benzene in technical grades (consisting of approximately 55% by weight of diviny] benzene and approximately 45% by weight of ethylvinyl benzene). 5 g of bcnzoyl peroxide. 1 liter of isooctane, 3 liters of deionized Wu tcr. 30 g of poly(sodium mcthacrylate), 30 g of sodium dihydrogen phosphate and 30 g of sodium chloride was charged into a l0-liter autoclave equipped with a thermometer. a nitrogen gas inlet tube and a mechanical stirrer. After the air in the upper space was replaced with nitrogen. the autoclave was scaled and stispcnsion polymerization was carried out in the autoclave at 80" C for 10 hours and at C for 10 hours. Subsequently, the resulting polymer beads were boiled in hot water to eliminate the isooctane and to produce opaque porous base resin beads.

The degree of crosslinking of the resulting base resin was l0/( and the specific surface area of the base resin measured by a BET type surface area measuring apparatus (nitrogen gas adsorbing method) was 26 m /g dry resin.

EXAMPLE C- Preparation of a halomethylatcd base resin In a lU-liter glass-lined autoclave equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube and a mechanical stirrer were charged 5 liters of chloromethylether and 1,000 g of the base resin beads which were obtained in the above Example A or B. The mixture was kept under nitrogen at 50 C for 2 hours with stirring, allowing the beads to swell sufficiently with chloromethylether.

Then, 250 g of anhydrous powdered zinc chloride were added in small portions over a period of l hour, after which the reaction was carried out with stirring at 60 C for 4 hours.

The resulting light yellowish beads were filtered off and washed with acetone and water in order to decompose the zinc chloride and to remove the excess of chlorornethylether.

The content of the chloromethyl group in the resin beads were determined by measuring the content of the chlorine according to the method of HS K6580. It was shown that 9 10 units of chloromethyl groups were introduced per lO units of aromatic nuclei initially contained in the base resin.

EXAMPLE I Into a l-liter, four-neckcd flask equipped with a ther mometer, a reflux condenser and a mechanical stirrer were charged 700 ml of dioxane and 50 g of chloromethylated base resin beads (containing 0.3 mole of chloromethyl group) which were prepared in accordance with the aforementioned Example C via A, the degree of crosslinking of which was 2.75% (a 50g) and the average diameter of which was 0.25 0.50 mm. The mixture was kept under nitrogen at l00 C for l hour with stirring, allowing the beads to swell sufficiently with dioxane. Then, 315 g (1 mole) ofN,N,N", N"'tetra (Z-cyanoethyl) diethylene triamine, the inter mediate of functional groups which was prepared by the Michael reaction of diethylene triamine with acry lonitrile, were introduced into the flask, and the mixture was kept at a reflux temperature for 15 hours with stirring. The reaction mixtures were then cooled and filtered. Light yellowish brown reaction products were obtained after washing with acetone and water.

The resulting reaction products were placed in a l liter. four-neckcd flask equipped with a thermometer,

a reflux condenser and a mechanical stirrer. Then. 500

ml of concentrated hydrochloric acid were added and the mixture was stirred at It reflux temperature for 5 hours to hydroly/c the nitrile groups of the int rmcdiate of functional groups introduced to the side chain on the base resins. The reaction mixtures were filtered and the resulting resin beads were thoroughly washed with water and immersed in an aqueous solution of sodium hydroxide in order to convert the carboxylic acid groups in the functional groups into sodium carboxyl ate groups. The final products were washed with water until no further pink color was detected with a phe nolphthalein indicator.

lt was confirmed that the nitrile groups in the beads were hydrolyzed completely by infrared spectrum analysis with almost no residual cyano groups detected. The final beads contained 1.64 mmole/g dry resin of chelate-forming functional groups. the content of the carboxyl group corresponded to 6.56 m eq./g dry resin, which were determined from the nitrogen contents by the Micro-Dumas method. The rate of conversion turned out to be as high as 97.5% of the theoretical amount based on the initial chloromethyl groups contained. The resulting chelating resin showed [.46 mmole/g dry resin (1 hour of adsorption time) and 1.63 mmole/g dry resin (2 hours of adsorption time) of the selective adsorbing capacity for cupric ions. From these results, it was determined that the selective adsorbing capacity for cupric ions was as high as 0.249 mole (2 hours of adsorption time) per unit mole of carboxyl groups.

lmorder to examine the elution properties of cupric ions from the saturated chelating resin with cupric ions, a deadsorbing test was carried out in aqueous solution at pH 2.0 as a batch operation. The degree of deadsorption was as high as 97.3% (2 hours of deadsorption time) of the total amount of the adsorbed cupric ions and they were regenerated easily at a very high yield. 0.5 N hydrochloric acid was fed as a regenerant at a rate of SV value of 2 1/1 resin.hr. by column operation to a bed of chelating resin saturated by cupric ions. When the amount of l 1/] resin of 0.5 N hydrochloric acid as the regenerant was passed through the column, it was found that the degree of regeneration of the resin bed in the column reached as high as 72.7%.

These results demonstrated that the process of this example gave a very effective way of introducing functional groups (consisting of diethylene triamine con taining two iminodipropionic acid groups) and that the resulting chelating resin had not only a high selective absorbing capacity for heavy metal ions, e.g. cupric ions in the presence of a large amount of alkali metal ions, but also ease of regeneration under mild conditions as compared to other chelating resins.

COMPARATIVE EXAMPLE 1 Example I was repeated, except using 123 g 1 mole) of iminodipropionitn'le instead of 3l5 g l mole) of N,N,N",N"-tetra (2cyanoethyl) diethylene triamine as an intermediate of functional groups. The amount of function] groups of the resulting sodium iminodipro pionate type resin, determined by nitrogen analysis, was 2.29 mmole/g resin (the content of the carboxyl group corresponded to 4.57 m eq./g resin), which was as low as 73.3% of the theoretical amount based on the amount of the initial chloromethyl group.

And the selective adsorbing capacity of this resin for cupric ions was 0.96 mmole/g dry resin (2 hours of adsorption time) and the adsorbed mount of cupric ions per unit mole of carboxyl groups was as small as 0.2 l mole (2 hours of adsorption time). Accordingly. when iminodipropionitrile was used as an intermediate of functional groups, the ratio of introduction of functional groups to the halomethylated base resin was relatively poor and accordingly the capability of selective udsorhtion of cupric ions was rather unsatisfactory.

COMPARATIVE EXAMPLE 2 When the elution properties of cupric ions from an adsorbent for cupic ions was examined under exactly the same conditions as in Example I using Diaion CR l0 manufactured by Mitsubishi Kasei Co., Ltd. of Japan as a resin having an iminodiacetate group as chclate-forming functional groups, the degree of desorption of cupric ions at pH 2.0 was l8.3% (2 hours of desorption time) and the degree of regeneration of the resin by 0.5 N hydrochloric acid was as low as 27.5%.

As compared with the iminodipropionic acid of Example l, the iminodiacetic acid was slow with respect to desorption speed of cupric ions, and in order to elute cupric ions completely, it was necessary to make the pH lower, or to use a larger amount of the regenerant, resulting in compelling strict conditions to the resin for regeneration; therefore, it had the drawback that the recycle lifetime was shorter.

COMPARATIVE EXAMPLE 3 into a flask the same as in Example I were charged 50 g of chloromethylated base resin beads (the content of the chloromethyl group of which was 0.3 mole) and 20 ml of chloroform, the resulting mixture was stirred at 60 C for l hour to swell the base resin beads. Subsequently. 400 ml of chloroform and 60 grams (0.43 mole) of hexamine were added into the flask and refluxed for 4 hours with stirring. The reaction products were filtered off and transferred into another flask, to which 150 ml of concentrated hydrochloric acid and 700 ml of ethyl alcohol were added. The resulting mixture was refluxed with stirring for 4 hours. Thereafter. the resulting resin was filtered and washed to obtain a base resin to which an aminomethyl group had been introduced. The amount of functional groups contained in the base resin wasa 3.01 mmole/g dry resin as a result of nitrogen analysis. Next, in a separately prepared l-liter flask, 87 g of B-chloropropionic acid was precisely neutralized with sodium hydroxide, continuously 38 g of the aforesaid aminomethylated base resin and 300 ml of ethyl alcohol were added into the flask, and the resulting mixture was reacted at C for 20 hours while an aqueous solution of sodium hydroxide was added thereto in a manner to keep the reactants always weakly alkaline. The reaction product was filtered, washed with water and ethyl alcohol and dried. The selective adsorbing capacity for cupric ions was measured. It was as low as 0.2] mmole/g dry resin (2 hours of adsorption time). And the number of carboxyl groups per unit functional group introduced, determined by measuring the exchange capacity of an ordinary wcakly acidic ion exchange resin, was 1.25. Accordingly, the degree of formation of the iminodipropionic acid groups was as low as 12.5% of the initial quantity of amino groups.

Although the reaction yield at the stage of con vcrting a halomethylutcd group to an aminomcthyl group wasa not so poor, it was relatively easy to introduce one pro pionic acid group to the amino group at the stage of adding sodium B-chloropropionate to crosslinked ami nated polystyrene. However, it was difficult simultancously to introduce two propionic acid groups. And it was not possible to form an iminodipropionic acid group effectively.

COMPARATIVE EXAMPLE 4 The selective adsorbing capacity for cupric ions was measured using Diaion pk 228" manufactured by Mit subishi Kasei Co., Ltd. of Japan as the strongly acidic cation exchange resin and Amberlite [RC-50 manufactured by Rohm and Haas Co. as the weakly acidic cation exchange resin. However, in the presence of large amounts of alkali metal ions, adsorption of cupric ions took place only very slightly.

COMPARATIVE EXAMPLE 5 In a flask the same as that in Example 1 were charged 50 g of chloromethylated base resin beads (the content of the chloromethyl group was 0.3 mole) and 700 ml of dioxane. and the mixture was stirred at 100 C for 1 hour to swell the resin. 103 g( 1 mole) of diethylene tri amine were added continuously into the flask. and the resulting mixture was reacted at a reflux temperature with stirring for 8 hours. The reaction product was filtered and washed with water and methanol to obtain a resin to which diethylene triamine groups had been introduced. The amount of functional groups contained in this resin was 2.88mmole/g resin, which was relatively large as a result of nitrogen analysis, however, the selective adsorbing capacity for cupric ions was as small as 0.34 mmole/g dry resin, much too low for practical performance.

When the polyalkylene polyamine functional group that was introduced contained no iminodipropionic acid group, the product had very poor ability to form a stable chelatc with cupric ions as a heavy metal selectively in the presence of a large amount of alkali metal ions and to adsorb cupric ions.

EXAMPLE 2 Example 1 was repeated, except using 360 g 1 mole) of N,N.N'-tri (carboethoxyethyl) ethylene diamine synthesized by blowing a dry hydrogen chloride gas into an ethanol solution of N.N,N'-tri (2-cyanoethyl) ethylene diamine which was obtained by the Michael addition reaction of aerylonitrile with ethylene diamine as an intermediate, instead of 315 g 1 mole) of N,N,N",N"-tetra (Z-cyanoethyl) diethylene triamine. The amount of functional groups in the resulting che lating resin. determined by nitrogen analysis. was 2.06 mmole/g dry resin (the content of the carboxyl group corresponded to 6.18 m eq./g dry resin), which showed the reaction yield was as high as 94.5% of the theoretical amount based on the initial amount of the chloromethyl group.

The selective adsorbing capacity for eupric ions was as high as 1.38 mmole/g dry resin 1 hour of adsorption time) and 1.59 mmole/g dry resin (2 hours of adsorption time).

The selective adsorbing capacity for cupric ions per unit mole of earboxyl groups was as high as 0.257 mole (2 hours of adsorption time).

As such. a chelating resin produced by hydrolyzing functional groups derived from ethylene dianiine hav ing an ethyl iminodipropionate group was high in introductory reaction yield of the functional group thereof and selectively adsorbed cupric ions as a heavy metal ion in the presence of a large amount of alkali metal ions.

EXAMPLE 3 In a l-litcr. four-necked flask equipped with a ther mometer. a reflux condenser and a mechanical stirrer were charged with 50 g of chloromethylated base resin beads having a degree of crosslinking of 2.75% and an average diameter of0.25 0.50 mm. obtained in Example C via A (the content ofthe chloromethyl group was 0.30 mole). 500 ml of dioxane, and the resulting mixture was stirred at C for 1 hour to swell the base resin sufficiently. A mixture of 103 g 1 mole) of diethylene triamine and 212 g (4 moles) of acrylonitrile was added dropwise continuously to the resulting mixture. After completion, the resulting mixture was reacted with stirring continuously at a reflux temperature for 15 hours.

Subsequently, the reaction product was filtered and washed with water and acetone to obtain a light yellow ish brown head. When this reaction product was pulverized and subjected to infrared adsorption spectrum analysis, a sharp absorption peak based on the cyano group was detected in the vicinity of 2240 cm, and it was confirmed that the acrylonitrile used was added to diethylene triamine by the Michael addition reaction. At the same time. it was introduced to the aromatic nuclei of the side chain of the crosslinked polystyrene.

Next, the entire amount of the reaction product was charged in another l-liter, four-necked flask equipped with a thermometer, a reflux condenser and a mechanical stirrer, into which 500 ml of concentrated hydrochloric acid was added. The resulting mixture was reacted at a reflux temperature with stirring for 5 hours to hydrolyze the nitrile group of an intermediate of functional groups introduced to the side chain of the base resin. Subsequently, the reaction product was filtered, thoroughly washed with water and thereafter immersed in an aqueous solution of sodium hydroxide to convert the carboxylic acid of the functional group into sodium carboxylate.

When the resulting reaction product was pulverized and subjected to an infrared adsorption spectrum anal ysis, the residual cyano group was barely detectable, and it was confirmed that hydrolysis was almost completc. The amount of functional groups in the resulting chelating resin, determined by nitrogen analysis, was 1.65 mmole/g dry resin, which showed the reaction yield was as high as 97.7% of the theoretical amount based on the initial amount of the chloromethyl group. The quantity of carboxyl groups in the resin determined by measuring the exchanging capacity of an ordinary weakly acidic ion exchange resin was 5.95 m eq./g dry resin. The yield of the Michael addition reaction of acrylonitrile diethylene triamine introduced to the base resin, calculated from said value, was as high as a 90.1%.

The selective adsorbing capacity for cupric ions of the resulting chelating resin was 1.44 mmole/g dry resin 1 hour of adsorption time) and 1.63 mmole/g dry resin (2 hours of adsorption time and the selective adsorbing capacity for cupric ions per unit mole of the carboxyl groups. was as high as 0.274 mole (2 hours of adsorption time).

As such. it was found that the chelating resin obtained by simultaneously reacting diethylene triamine and acrylonitrile with crosslinked chloromcthylated polystyrene. and thereafter hydrolyzing the reaction product with hydrochloric acid, had at least 2 carboxyl groups per single introduced functional group. and introductory reaction yield of functional groups thereol and the degree of formation of the iminodipropionic acid group thereof were high. They had excellent ability to form a chelate with cupric ions as the heavy metal the initial amount of the chloromethyl group. The se lective adsorbing capacity tor cupric ions was as high as 1.20 mmole/p dry resin (2 hours of adsorption time).

ion in the presence of a high concentration of alkali 5 EXAMPLES 5 10 metal ions. and to adsorb the cupric ions thereby. When a flask and a base resin the same as in Example EXAMPLE 4 1 were used and reaction conditions were aried as shown in Table l. a high-performance chelating resin Example 1 was repeated except for using mac- H) was obtained at a high yield in each example. Table l roreticular type resin beads having a degree of cross shows the results actually obtained. linking of 10% obtained in Example C via B as the base resin to obtain a chelating resin. The amount of func- EXAMPLES l l l2 tional groups of this chelating resin. determined by ni- When a flask and a base resin the same as in Example trogen analysis was 1.04 mmole/g dry resin (the con- Is 3 were used and reaction conditions were varied as tent of the carboxyl group corresponded to 4.16 m shown in Table 2. a high-performance chelating resin eqr/g dry resin), which showed the reaction yield was was obtained at a high yield in each example. Table 2 as high as 87.4% of the theoretical amount. based on shows the results actually obtained.

Table l l-.\- Intermediates of functional group l-"uuclional groups ample of the linull resulting chulatlug remix untentinted li -liothlorit .11 ill lall lc I \ltrin structural \mlts lur lhL 1. A chelating resin having a crosslinlged polymer structure whose main structural unit is selected from the group consisting of the following (I) and (II) 0 8, n is an integer from 2 12, M represents hydrogen, a univalent ion selected from the group consisting of sodium, potassium, lithium and NH R designates hydrogen or a methyl group, X, Y and Z each represents hydrogen or a group selected from the class consisting of an alkyl group having 1 8 carbon atoms. a hydroxyalkyl group having I 8 carbon atoms an aromatic group having 6 9 carbon atoms an aralkyl group having 7 l0 carbon atoms and ACOOM, wherein A represents a divalent alkyl residual group having 1 8 carbon atoms and M is as heretofore stated.

2. A chelating resin having a crosslinked polymer structure, the main structural unit of which is 3,899,472 21 22 H)- wherein I is an integer from l 8, m is an integer from O 8, u is an integer from 2 l2, M represents hydrogen. 2! univalent alkaline ion selected from the group cairn-1010M consisting of sodium, potassium, lithium and NH,+, R (H NcHwcHcN 5 designates hydrogen or a methyl group, X, Y and Z 2 L \CHWCHQCOOM each represents hydrogen or a group selected from the L CH COOM class consisting of alkyl having 1 8 carbon atoms, hy-

droxyalkyl having 1 8 carbon atoms, aromatic having 6 9 carbon atoms, aralkyl having 7 carbon atoms and ACOOM, wherein A represents a divalent alkyl residual group containing l 8 carbon atoms.

5. A process for preparing a chelating resin having a crosslinked polymer structure whose main structural unit is hereinafter defined as a structure selected from wherein M represents hydrogen or a univalent ion se- 10 lected from the group consisting of sodium, potassium, lithium and NH 3. A chelating resin having a crosslinked polymer structure whose main structural unit is the group consisting of Q a n djll), whichwo ce s s com 2" plises rgaeting simultaneously a halomethyl group bonded to aromatic nuclei of a crosslinked polymer CH,CH,COOM consisting mainly of an aromatic vinyl monomer with f H COOM .(A) a polyalkylene polyamine derivative having in the 2 molecule at least one"'primary amino group and one H-.' 2 secondary amino group and (B) at least one unsaturated compound selected from the group consisting of acrylonitrile, methacrylonitrile, alkyl acrylate and alkyl methacrylate wherein the alkyl groups have I 8 carwherein M represents hydllogen m a upwalent i sebon atoms in the presence of a swelling solvent, therefrom the group conslstmg of sodium potassium after hydrolyzing the reaction product in the presence hthmm and I of an acid or alkali to produce at least one group seprocess for preparing a chglanng gi gz g tg i lected from the class consisting of iminodipropionic l i a i gi giz f of (I) and acid, iminodi-ot-methylpropionic acid, iminodipropiom mm is ecte mm e p l th I ate and immodl-a-methylproplonate, said structural which process Con-prises Feactmg a ome y units (l) and (ll) being defined as follows: group bonded to aromatic nuclei of a crosshnked polymer consisting mainly of an aromatic vinyl monomer CH* with a polyalkylene polyamine derivative (intermediate 2 of a functional group) having in the molecule at least one group selected from the class consisting of iminodipropionitrile, iminodi-wmethylpropionitrile, alkyl c'HfiNkmHnThN iminodipropionate and alkyl iminodi-a- 2 \cmCHCOOM methylpropionate wherein the alkyl groups have 1 8 1 carbon atoms, and at the same time, having at least one 40 HCH2)" fix primary and/or secondary amino group in the presence If of a swelling solvent, thereafter hydrolyzing the reaction product in the presence of an acid or alkali to produce at least one group selected from the class consisting of iminodipropionic acid, iminodi-a- 2 methylpropionic acid, iminodipropionate and R iminodi-oz-methylpropionate, wherein said structural 4 units (l) and (II) are: /CH: HCOOM cHlN-(CH- i l-N-(CHMN CH,IHCOOM -(-cn -cn+ 2 I i R CH dHCOOM (Ill I M wherein l is an integer from 1 8, m is an integer from 0 8, n is an integer from 2 l2, M designates hydrogen, a univalent alkaline ion selected from the group I consisting of sodium, potassium, lithium and NH R represents hydrogen or a methyl group, X, Y and Z each represents hydrogen or a group selected from the (mu CI". class consisting of an alkyl group having 1 8 carbon atoms, a hydroxyalkyl group having I 8 carbon T atoms, an aromatic group having 6 9 carbon atoms,

HZCHUDM 65 an aralkyl group having 7 l0 carbon atoms and CH tN CH. mfN- (iii-mllll) ACOOM, wherein A represents a divalent alkyl l, 00M residual group having 1 8 carbon atoms and M is as heretofore defined.

6. A process according to claim 4 wherein said inter mediate of the functional group is and/or HNCH CH- N \CHZCHUCN mately 60 20% of ethylvinyl benzene 

1. A CHELATING RESIN HAVING A CROSSLINKED POLMER STRUCTURE WHOSE MAIN STRUCTURE UNIT IS SELECTED FROM THE GROUP CONSISTING OF THE FOLLOWING (1) AND (11)
 2. A chelating resin having a crosslinked polymer structure, the main structural unit of which is
 3. A chelating resin having a crosslinked polymer structure whose main structural unit is
 4. A process for preparing a chelating resin having a crosslinked polymer structure whose main structural unit is selected from the group consisting of (I) and (II), which process comprises reacting a halomethyl group bonded to aromatic nuclei of a crosslinked polymer consisting mainly of an aromatic vinyl monomer with a polyalkylene polyamine derivative (intermediate of a functional group) having in the molecule at least one group selected from the class consisting of iminodipropionitrile, iminodi- Alpha -methylpropionitrile, alkyl iminodipropionate and alkyl iminodi- Alpha -methylpropionate wherein the alkyl groups have 1 - 8 carbon atoms, and at the same time, having at least one primary and/or secondary amino group in the presence of a swelling solvent, thereafter hydrolyzing the reaction product in the presence of an acid or alkali to produce at least one group selected from the class consisting of iminodipropionic acid, iminodi- Alpha -methylpropionic acid, iminodipropionate and iminodi- Alpha -methylpropionate, wherein said structural units (I) and (II) are:
 5. A process for preparing a chelating resin having a crosslinked polymer structure whose main structural unit is hereinafter defined as a structure selected from the group consisting of (I) and (II), which process comprises reacting simultaneously a halomethyl group bonded to aromatic nuclei of a crosslinked polymer consisting mainly of an aromatic vinyl monomer with (A) a polyalkylene polyamine derivative having in the molecule at least one primary amino group and one secondary amino group and (B) at least one unsaturated compound selected from the group consisting of acrylonitrile, methacrylonitrile, alkyl acrylate and alkyl methacrylate wherein the alkyl groups have 1 - 8 carbon atoms in the presence of a swelling solvent, thereafter hydrolyzing the reaction product in the presence of an acid or alkali to produce at least one group selected from the class consisting of iminodipropionic acid, iminodi- Alpha -methylpropionic acid, iminodipropionate and iminodi- Alpha -methylpropionate, said structural units (I) and (II) being defined as follows:
 6. A process according to claim 4, wherein said intermediate of the functional group is
 7. A process according to claim 4, wherein said crosslinked polymer consisting mainly of an aromatic vinyl monomer is substantially a copolymer of styrene and divinyl benzene in technical grade (consisting of approximaTely 40 - 80% of divinyl benzene and approximately 60 - 20% of ethylvinyl benzene). 